The present invention relates to a method and apparatus for forming a compressed bar from an oil seed crop. More particularly, the present invention relates to a press assembly and method for forming a compressed bar or block from an oil seed crop in which the bar contains substantially the full fat content of the oil seed crop. The compressed bar does not require the use of binders to hold the bar together.
Conventional oil seed crop processors separate oils from the meal of oil seed crops and sell the oil and the meal as separate products. Typically, hexene is used to extract all the oil from the oil seed crop. The hexene is then removed from the mixture. However, trace amounts of the hexene may remain in the oil removed using this method. Since the oils are removed from the meal, USDA approved binders must be added to the meal to slow water penetration into the meal. Compressed bars formed from meal which contains such binders typically repel water for only about 24 hours. After that time, the bars tend to disintegrate.
Conventional oil seed crop pellet-forming methods teach that the fat must be removed from meal in order to form a compressed pellet or block from the oil seed crop. The conventional pellet formation methods then use added chemical binders to hold the meal together in pellet form.
An object of the present invention is to provide a method and apparatus for forming a compressed bar from oil seed crops without the use of binders.
Another object of the present invention is to improve the resistance of compressed bars made from oil seed crops to moisture.
Pure vegetable oils are non-emulsifiable or non-soluble with water. In other words, pure vegetable oils will not mix with water. The present invention provides an apparatus and method for making compressed bars from an oil seed crop in which the bars retain substantially all the oil from the oil seed crop. Therefore, water cannot penetrate the compressed bars of the present invention.
Yet another object of the present invention is to provide a compressed full-fat oil bar made from oil seed crops to reduce the volume of material in a container, thereby reducing shipping costs for the product. This is especially important when shipping product overseas because product volume, not weight, is the limiting factor for shipping costs. The present invention reduces the volume of the oil seed crops to about one third the volume of the bulk material. This reduces overseas shipping costs substantially.
Still another object of the present invention to form compressed bars from an oil seed crop while maintaining the fatty acid contained in the oil seed crop in the compressed bars, thereby improving the nutritional value of the compressed bars. The compressed bars made from an oil seed crop are typically used for fish food for farm-raised fish, for fish or lobster bait, or for a food source for other animals or humans.
The apparatus and method of the present invention permits formation of compressed bars or pellets without removing oil and fat from the oil seed crop, thereby improving the levels of important fatty acids in the pellets. This improves the nutritional value of the compressed bars and pellets made from the oil seed crops.
The compressed bar of the present invention advantageously increases the quality of farm raised fish which may feed on the compressed bars of the present invention. Typically, fish raised in commercial fish farms have relatively low levels of omega-3 fatty acid. Omega-3 fatty acid is the type of fatty acid considered to be responsible for lowering cholesterol levels in the human body. A wild fish typically contains approximately 14% omega-3 fatty acid, while fish from farm raised ponds typically have less than 2% omega-3 fatty acid. This large difference is because current fish feeds do not contain adequate levels of omega-3 fatty acid. Compressed bars made from soybeans according to the present invention typically have about 8% omega-3 fatty acid content. In addition, flax can be added to the product to increase the omega-3 fatty acid content even more. Flax oil typically contains about 57% omega-3 fatty acid. By increasing the level of omega-3 fatty acid in the fish food, the level of omega-3 fatty acid in the fish also increases.
Forming compressed bars and pellets without removing the oil from the oil seed crops provides another important advantage as discussed above. Water cannot penetrate the compressed bars or pellets which include the oil from the oil seed crop. This improves the life of the bars or pellets when immersed in water for fish feed. The oil remaining in the bars or pellets also keeps the products from molding, even in high humidity conditions. This is important when the bars or pellets are stored in humid areas such as Florida or the Bahamas.
Soybeans or other oil seed crops are used to make the compressed bars or pellets. Typically the oil seed crop is ground with a typical feed grinder. The grinders are a common apparatus on most livestock farms. Although the product does not necessarily need to be ground, grinding generally improves the output of the processor by about 25%. The ground oil seed crop is passed through an extruder which augers the oil seeds through a series of steam locks until the product exits a hole in the end of a barrel that has a small area. The extruder heats the extruded product to about 270.degree. F. in about 15 seconds. The apparatus and method of the present invention works best with the extruder running about 270.degree.. If soybeans are being extruded, the temperature must remain at 270.degree. or higher in order to kill inhibitors. The extruded product exits the extruder in a semi-liquid state.
The semi-liquid product drops directly into an insulated housing tub located on a load barrel assembly of the present invention. The semi-liquid oil seed product must remain hot until the load barrel assembly distributes the product into the cooling die assembly. A hydraulic ram retracts to allow a metered amount of the hot semi-liquid oil seed product to drop into an over-sized load barrel. When the ram contacts a reversing switch, the hydraulic piston inside a cylinder assembly extends the ram to apply about 38,000 pounds of pressure against the oil seed product in the load barrel. This pressure forces oil to leave the meal in the product. However, because the load barrel is a closed system, the oil cannot escape and must remain with the meal. The oil seed product is forced into a tube of the cooling die assembly. The tube of the present invention is preferably at least 30% smaller than the output of the load barrel. If the tube is any larger, the hydraulic cylinder cannot develop the high pressure required for oil extraction.
In one embodiment of the present invention the cooling die is about 20 feet long and includes a 4-stage cooling assembly. Water is circulated through the cooling dies to cool the product. The first cooling stage maintains the product at a predetermined threshold temperature of about 180.degree. F. or higher. If the first cooling stage cools the product below about 180.degree. F., the compressed bars made by the press assembly tend to break. Inside the cooling die, the meal absorbs the hot runny oil. As it does, the product expands in the cooling die. This expansion creates extremely high side load pressures on the tube walls of the cooling die, thereby causing the product to plug within the cooling die. When the ram reloads and tries to press additional product into the cooling die, the cylinder has to develop enough pressure to unplug the die. If the product in the cooling die is cooled too rapidly, the product will absorb the oil and shrink as it is cooled. Therefore, the die would not be plugged and the cylinder could not develop the pressure required to extract the oil from the semi-liquid oil seed mixture.
The combination of an over-sized load barrel and high side load pressures from the expanding product causes the compressed bar to have all the oil and fatty acid that existed in the oil seed crop. As the product moves through the remaining three cooling stages, it becomes important to cool the product as rapidly as possible. Therefore, extra length for extra cooling capacity is added. One reason for quickly cooling the product is that over cooking the product can destroy the protein content of the product. In addition, the oil must be thickened so that it will not drip out of the finished product. When the oil recombines with the meal, it sets up as if it were a wax. This waxed oil will not mix with water and thereby repels water from entering the feed. The oil also keeps the product from molding, even in high humidity conditions.
Once the compressed bar exits the cooling die, the bar comes into contact with a stop block on a sliding cutting table. As the table moves, a normally open switch moves to its open position and causes a vertical saw to drop through the compressed bar, thereby cutting the bar into smaller bars having a predetermined length depending on the position of the stop block. Normally the bars are cut to be about 11.75 inches long. After the saw completes the cut, an air cylinder pushes the cut bar off the sliding cutting table and onto a conveyor belt located adjacent the sliding cutting table. Another air cylinder then relocates the sliding table for the next cut.
According to one aspect of the present invention, an apparatus is provided for forming a compressed bar from an oil seed crop including oil and meal. The apparatus includes means for heating the oil seed crop to a predetermined temperature, a load barrel having an inlet for receiving the oil seed crop from the heating means and an outlet, and a ram located inside the load barrel. The apparatus also includes a cooling die assembly having a tube for receiving the oil seed crop therein. The tube has an inlet end coupled to the outlet of the load barrel and an outlet end. The cooling die assembly also includes means for cooling the oil seed crop as it passes through the tube. The apparatus further includes means for moving the ram back and forth inside the load barrel to force the oil seed crop through the outlet of the load barrel and through the tube of the cooling die assembly to form the compressed bar which includes both the oil and meal from the oil seed crop as the oil seed crop is forced through the tube by the ram.
In the illustrated embodiment, the cooling means includes a first cooling stage coupled to the tube adjacent the outlet of the load barrel. The first cooling stage maintains the temperature of the oil seed crop at a temperature above a predetermined threshold temperature. The cooling die assembly also includes at least one additional cooling stage for cooling the oil seed crop further after it passes through the first cooling stage.
Each cooling stage includes a cooling jacket surrounding the tube and means for circulating water through the cooling jacket to cool the oil seed crop passing through the tube adjacent the cooling jacket. The first cooling stage includes a thermostat coupled to the circulating means to maintain the temperature of the oil seed crop in the first cooling stage at a temperature above the predetermined threshold temperature.
A substantial amount of pressure is required to form the compressed bar in the tube. Therefore, the inlet of the tube has an inlet area which is smaller than an outlet area of the outlet of the load barrel, thereby causing the oil seed product to plug inside the tube and increasing the pressure required to push the oil seed crop through the tube of the cooling die assembly. In the illustrated embodiment, the inlet area of the tube is at least 30% smaller than the outlet area of the outlet of the load barrel. The ram applies at least 38,000 pounds of pressure against the oil seed crop to form the compressed bar in the tube.
Also in the illustrated embodiment, the heating means includes an extruder for extruding the oil seed crop before the oil seed crop enters the load barrel. The extruder heats the oil seed crop to a predetermined temperature to form a semi-liquid product from the oil seed crop. The apparatus further includes an insulated tub coupled to the inlet of the load barrel. The insulated tub receives the semi-liquid product from the extruder and delivers the semi-liquid product to the load barrel as the ram moves back and forth inside the load barrel.
The moving means includes a hydraulic piston and cylinder coupled to the ram. The moving means also includes means for automatically controlling movement of the piston inside the cylinder coupled to provide reciprocating movement of the ram inside the load barrel. The apparatus also includes means for cutting the compressed bar into a plurality of smaller bars as the compressed bar exits the outlet end of the tube.
In another illustrated embodiment, the cooling die assembly includes a plurality of tubes coupled to the outlet of load barrel to form a plurality of compressed bars as the oil seed crop is forced through the plurality of tubes by the moving means. In this embodiment, the cooling means includes a cooling jacket surrounding a portion of the plurality of tubes and means for circulating water through the cooling jacket to cool the oil seed crop passing through the plurality of tubes. The cooling jacket surrounding a portion of the plurality of tubes is spaced apart from the inlet of the plurality of tubes to provide an uncooled entry section adjacent the outlet of the load barrel.
According to another aspect of the present invention, a method is provided for forming a compressed bar from an oil seed crop including oil and meal. The method includes the steps of heating the oil seed crop to a predetermined temperature and form a semi-liquid product and loading the semi-liquid product into an inlet of a load barrel. The load barrel has an outlet with a predetermined outlet area. The method also includes the step of applying pressure to the oil seed crop in the load barrel to force the oil seed crop into a tube having an inlet coupled to the outlet of the load barrel. The inlet of the tube has an inlet area which is smaller than the outlet area of the outlet of the load barrel, thereby increasing the pressure required to push the oil seed crop through the tube. The method further includes the steps of cooling the semi-liquid product in a first cooling stage located adjacent the outlet of the load barrel to a predetermined threshold temperature, and further cooling the semi-liquid product after the oil seed crop passes through the first cooling stage to form the compressed bar which contains both the oil and meal from the oil seed crop.